Adjustable mold for casting a concrete stairway

ABSTRACT

An adjustable mold for casting stairways of concrete enables the total length of a stairway and also the dimension of the separate steps to be adjusted. The mold includes a longitudinal horizontal frame supporting two identical parallel articulated arm systems positioned scissor-like and being linked together at intersection points of arms of the system along a longitudinal center axis thereof. At oppositely located and linked outer ends of the arms are provided pivotable supports for a number of step units, each of which includes an upstep and an instep. An inner edge of each instep substantially by its own weight rest against the upstep of an adjacent step unit. The total length of the articulated arm link system may be adjusted, thereby simultaneously adjusting the distance between adjacent step units. Also, the angular position of the step units relative to the support frame can be adjusted.

BACKGROUND OF THE INVENTION

The present invention relates to casting equipment for production ofstairways or staircases of concrete, and more particularly to anadjustable casting mold for production of stairways having variouslengths, climbing heights, and number of dimensions of separate steps ofthe stairway.

In order to meet specifications for stairways for different individualbuilding constructions, the building industry substantially has beenrequired to have available a large number of different casting molds, asituation which obviously is rather cumbersome and expensive, amongother things due to storage space requirements. Frequently it occursthat available casting molds do not have the specifications required fora particular construction, such that special casting molds still must bemade, either in a factory or at the building site.

There are a number of known proposals for adjustable casting molds forcasting stairways of concrete, but such known designs hitherto have notbeen very successful, partly because the constructions have been rathercomplicated and cumbersome both in construction and use, especiallybecause the possibilities for adjustment have not proved to besufficient. Illustrative prior art systems are disclosed in GermanPatent No. 35 18 200, German published Patent Application No. 21 55 577and No. 24 07 871, French Patent No. 2 332 685 and Swedish Patent No.425 572.

SUMMARY OF THE INVENTION

The casting mold in accordance with the present invention provides, inspite of a relatively simple construction, possibility for a very largenumber of adjustments, such that it is possible to produce stairways andstaircases which meet substantially about any and all differentspecification requirements. With a pair of manual adjustments it ispossible, in a stepless manner, to adjust the length, climbing height,number of steps and dimensions of upsteps and insteps of the stairway.

The casting mold in accordance with the invention is generallycharacterized by the following features:

a longitudinal, horizontally extending supporting frame includesparallel, longitudinal supporting elements,

two mutually identical, articulated link arm systems displaceablyarranged on the supporting frame and are pivotally linked together in ascissors-like manner at points of overlapping intersection of arms ofthe systems crossing a longitudinal center line of the systems,

opposing outer points of articulation of the arms support a plurality ofstep units in such fashion that the step units can undergo verticalpivotal movement,

each step unit includes an instep and an upstep interconnected to form aright angle,

there is provided means for adjusting the total length of thearticulated link arm systems, thereby simultaneously adjusting thedistance between adjacent step units, and means for adjustment of theangular position of the step units relative to the supporting frame.

With a casting mold in accordance with the invention it is possible bymeans of two simple separate adjustments to accomplish a steplessadjustment of the length of the stairway and the position of each stepunit. By such adjustments it also is possible to define the number ofsteps required in the stairway to be built, the climbing height of thestairway as a whole and the climbing height of each upstep of thestairway.

Through simple adjustments it also is possible to adjust the depth ofthe insteps of the stairway.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention shall be further described with reference to theaccompanying drawings which in detail illustrate an embodiment for acasting mold in accordance with the invention, and wherein:

FIGS. 1 and 2 are a lateral view and a plan view, respectively, of acasting mold in accordance with the invention;

FIG. 3 is an end view seen from the left side of the mold as shown inFIG. 1 and on a somewhat enlarged scale;

FIG. 4 is a detailed lateral view on a further enlarged scale and whichillustrates the construction of steps or step units and the functionthereof;

FIG. 5 is a fragmentary sectional view along plane V--V in FIG. 1 whichillustrates on an enlarged scale, a right half part of the mold andwhich especially illustrates a side part of the mold and the adjustmentof the width of the casting mold and a stairway made thereby; and

FIG. 6 is a fragmentary side view along plane VI--VI in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIGS. 1, 2 and 3, a casting mold comprises a support frame 1including three longitudinal support beams provided with superimposedtransverse beams. On top of beams 3 are positioned four longitudinalchannel-shaped beams 4 which form support for two identical arm linksystems 6 and 8 which are arranged in a symmetrical scissors-likeformation and are interlinked at intersection areas or midlengthportions 9 thereof along the center line of the structure by means ofcenter pivot bolts 10. The bolts 10 are further supported on saddle-likechannel brackets 17 which are displaceably mounted between the twocentral channel beams 4. The separate arms in the two arm link systems 6and 8 are further linked together at opposite lateral ends thereof bymeans of end pivot bolts 11, 13. As best shown in the plan view of FIG.2, the link points between each pair of arms of one system arepositioned directly opposite to link points between each pair of arms ofthe other system, relative to the longitudinal center axis of thestructure. Each of the pivot bolts 11, 13 forms a support for a supportsabot 14, the design of which best appears from the detail view shown inFIG. 4.

As best appears from FIGS. 1 and 4, the course of the stairway is builtup by means of step units 16 each of which comprises an "upstep" 18 andan "instep" 20. The upstep 18 includes two or more support brackets 22each of which defines a right angle and is welded, at a lower edge ofthe upstep, to a transverse rod or shaft 24 which is pivotably arrangedin the transverse direction of the structure and is displaceablysupported by respective of the sabots 14. The brackets 22 form supportfor the insteps 20. The insteps 20 preferably are releasably attached tothe brackets 22 by means of screws 26 or the like, enabling an operatorto install insteps having various depths. In the illustratedembodiments, at a corner zone of bracket 22 between the upstep andinstep is provided a list 23 which constitutes a section of the instepand is adapted for receipt of the instep via a tongue and grovearrangement or the like. As shown in FIGS. 1 and 4, longitudinal edges25 of the insteps rest with their weight loosely against the respectiveadjacent upsteps 18.

The two link arm systems are, via the undermost positioned arms,looseably and slideably biased against the outer channel beams 4. On topof these channel beams 4 may, if desired, be positioned longitudinalslide strips 27 as shown in FIG. 3.

At the left end of the two arm link systems 6 and 8 the last or endmostpair of arms 29, 31 are pivotally supported on pivot bolts 28 whichfurther are supported on collar-like brackets 30 which are laterallydisplaceably supported on a transverse element 32 attached on the topside of the support frame. Thereby, the ends of the scissor arms orpairs of arms on either side of the central line thereof may moveinwardly and outwardly relative thereto during the extension andcontraction, respectively, of the arm system.

The casting mold provides two possibilities for stepless adjustment,namely a first stepless adjustment of the length of the stairway andthereby the distance between each separate step by means of the scissorsarm system, and a second adjustment of the dimensions of the separatesteps.

The length of the scissors arm system of the illustrated embodiment isadjusted by means of a worm screw 42 which at the right end thereof asshown in FIG. 2 can be connected to an electrical motor 44 via areduction gear or the like. On the worm screw is positioned a threadedbushing 46 which is attached to one of the brackets 12 which formsupport for one of the pivot bolts 10 of the scissors arm system. Itwill be understood that when such one bracket 12 and the respectivepivot bolt 10 thereof is displaced forwardly or backwardly, such willcause the entire scissors arm system to be extended or shortened,respectively.

The angular position of the step units is adjusted by means of alongitudinally adjustable element such as a worm screw 50 or the likewhich is supported at one end thereof at a pivot point 51 on the last orendmost step 52 to the left as shown in FIG. 1 and at another endthereof at a pivot point 53 on the support frame 2. When, for example,the element 50 is extended, the last step 52 will be forced upwardly.This will cause all of the step units simultaneously to be pivotedupwardly in a corresponding manner since the end edge 25 of each instepwill slide or be displaced upwardly along the adjacent upstep, such thatthe actual height of the upstep will be correspondingly reduced.

The width of the casting mold and thereby the width of the stairwaymolded therein can be adjusted in several different ways. In theillustrated solution, the mold surfaces for the lateral sides of thestairway are provided by means of adjustable posts 60 which are bestshown in FIG. 5 and which on the inside thereof are provided with moldplates or wall members 62. The posts 60 with corresponding structurethereof are laterally displaceable, preferably by means of rollers 64which are biased against the lateral beams 3 of the support frame. Theposts 60 include lateral plates 68 which are biased against respectiveexternal sides of the lateral beams 3 and which thereby hold and guidethe posts. The posts may be locked in position by means of bolts or thelike, not shown. For determination of the width of the stairway one canarrange either one step unit for each width with upsteps and insteps or,in a preferred embodiment, one utilizes lining boxes which arepositioned on the steps against the mold plates 62, as indicated in FIG.5 by dashed lines 65.

The illustrated casting mold in accordance with the invention willoperate and be used in the following fashion. In the making of an actualstairway the specifications of the stairway usually will be given, forinstance the vertical height between two floors in question, thehorizontal projection of the stairway, and possibly also the desirednumber of steps in the stairway based on the total height. A normalheight of the upsteps is 15 to 18 cm. On this basis the requirednecessary length of the stairway is determined, and further determinedis the suitable number of steps of the stairway if such value is notprovided in the specifications. The illustrated casting mold includesaltogether up to 23 possible step units. A straight stairway with morethan 23 steps seldom is case. If the stairway is to be produced with,for instance, fourteen steps, the length of the casting mold is definedby means of the worm screw arrangement 40 until the desired length hasbeen set. Thereafter, the angular position of the step units is adjustedby means of the adjustment element 50 by which the elevation or heightof the steps is calibrated or set. In some cases it will be determined,during adjustment of the casting mold, that the number of steps of thestairway shown be increased or possibly reduced by one step. Suchreadjustment can simply be carried out by extending or shortening,respectively, the distance L between adjacent steps and by a suitablereadjustment of the height of the upsteps by means of a correspondingadjustment of the angular position between each of the step units.Thereafter the casting mold is closed off at opposite ends by means ofstandardized termination units 70, 73, 75 (shown by dashed lines in FIG.1), in order to cast landings at the top and at the bottom of thestairway.

When the various adjustments of the casting mold have been finalized,the mold is filled with concrete up to the top edge of the mold andfurther the separate mold units at each end are filled in order to formthe desired landings at the top and at the bottom of the stairway. Thetop surface of the mold (the under side of the stairway) is thereafterstripped off by means of a stripping member, whereafter the moldedsurface, if desired, is dressed or polished.

The depth of the insteps may be adjusted by means of the casting mold inaccordance with the invention. Insteps normally are specified to be ofvarious depths, namely 250, 272, 300 and 325 mm. To form stairways withthe beforementioned different depths there may be provided sets orinsteps of such depths. The desired set of insteps is mounted on thesupport brackets 22 as shown best in FIG. 4. When mounting, forinstance, deeper insteps one must normally readjust the distance Lbetween each step unit, i.e. extend this dimension, in order to maintaina correct angle between the insteps and upsteps.

It will be understood that, by means of the casting mold in accordancewith the invention, it is possible to carry out a substantially steplessadjustment of the different specifications of the stairway including thelength of the stairway, the dimension between adjacent steps, and theheight of the upsteps. Further, by employing insteps of differentdepths, it also is possible to form stairways with varying instepdepths. Also, the lateral dimension of the stairways may be adjusted ina very simple fashion.

I claim:
 1. An adjustable mold for casting concrete stairways ofselected different dimensions, said mold comprising:a longitudinal,substantially horizontal supporting frame; a pair of identical link armsystems defined by respective pluralities of link arms of equal lengthand supported on said supporting frame for displacement longitudinallythereof; each said link arm of each said link arm system being linked ata mid-length position thereof by a respective center pivot to arespective said link arm of the other said link arm system, such thatsaid link arms of said pair of link arm systems are coupled successivelyin pairs of arms with the respective said center pivot of each said pairof arms being positioned along a longitudinal center line of said pairof link arm systems; said arms of said pairs of arms having oppositeends linked by respective end pivots to respective ends of arms ofsuccessive adjacent pairs of arms, such that said end pivots are locatedin pairs on opposite sides of said longitudinal center line with saidend pivots of each pair of end pivots being positioned along a lineextending transverse to said longitudinal center line; a plurality ofstep units, each said step unit including an instep and an upstep, eachsaid instep having a transverse edge resting against an upstep of anadjacent step unit; means, mounted on said end pivots of each said pairof end pivots, for supporting each respective said step unit forvertical pivotal movement about a respective axis extending along alower end of the respective said upstep; means for moving at least oneof said center pivots longitudinally of said supporting frame, therebyeffecting simultaneous extension or retraction of said pair of link armsystems, and thus adjusting the spacing between steps to be formed byadjacent said step units; and means for adjusting the relative angularposition of said step units about said axes thereof.
 2. A mold asclaimed in claim 1, wherein outer portions of said link arms aresupported displaceably by outer longitudinal portions of said supportingframe on respective opposite sides of said longitudinal center line. 3.A mold as claimed in claim 1, wherein said supporting frame includesmeans for guiding movement of said center pivots along said longitudinalcenter line.
 4. A mold as claimed in claim 3, wherein said guiding meanscomprises longitudinal center guides spaced on opposite sides of saidlongitudinal center line.
 5. A mold as claimed in claim 4, furthercomprising brackets supporting respective said center pivots andpositioned for longitudinal movement between said center guides whilebeing guided thereby.
 6. A mold as claimed in claim 5, wherein saidmoving means comprises a worm screw mounted on said supporting frame andthreadingly engaging one of said brackets.
 7. A mold as claimed in claim1, wherein said moving means comprises a worm screw mounted on saidsupporting frame and operably connected to said at least one centerpivot to cause, upon rotation of said worm screw, movement of said atleast one center pivot longitudinally of said supporting frame.
 8. Amold as claimed in claim 1, wherein said supporting means comprises, foreach said step unit, a transverse shaft having opposite ends supportedby the respective said pair of end pivots and defining said axis.
 9. Amold as claimed in claim 8, wherein each said upstep includes at leastone bracket connected to the respective said shaft for mounting of therespective said instep.
 10. A mold as claimed in claim 9, wherein saidbracket defines a right angle between said upstep and said instep.
 11. Amold as claimed in claim 1, wherein said insteps are formed of pluralparallel parts that are selectively removable to thereby adjust thedepth of said insteps.
 12. A mold as claimed in claim 1, comprisingplural sets of said step units having different lateral dimensions andselectively removably mountable in said mold, thereby to cast stairwaysof correspondingly different lateral dimensions.
 13. A mold as claimedin claim 1, further comprising wall members mounted relative to saidsupporting frame to define lateral sides of the stairway to be cast. 14.A mold as claimed in claim 13, wherein said wall members are adjustablymounted on said supporting frame.
 15. A mold as claimed in claim 13,wherein said wall members are selectively replaceably mounted on saidsupporting frame.
 16. A mold as claimed in claim 13, further comprisinglining boxes selectively removably mounted at opposite sides of saidstep units and confronting said walls members, thereby to enable thelateral dimension of the cast stairway to be adjusted.
 17. A mold asclaimed in claim 1, further comprising supplemental mold members fordefining end or landing portions of the cast stairway.
 18. A mold asclaimed in claim 1, wherein said adjusting means comprises an adjustableelement operatively mounted between said supporting frame and one ofsaid step units.
 19. A mold as claimed in claim 18, wherein saidadjustable element comprises a worm screw.